1. Field of the Invention
This invention relates to a process for the vacuum deposition of metal (metal oxide and/or metal sulfide) layers on to substrates and to the articles produced thereby. The process provides for continuous application of materials to various substrates in a rapid fashion. Various metals may be oxidized in the coating procedure.
2. Description of the Prior Art
The vacuum deposition of metals and metal oxides to substrates has been practiced for many years. The uses for such metallized articles are well known and varied. The application of a metal to a surface has provided either optical qualities, such as mirror-like or reflective surfaces, or light transmissive surfaces (e.g., U.S. Pat. No. 4,190,321). Metal layers and metal oxide layers made by a batch process have also been provided for their contribution of electrical (e.g., conductive or semiconductive) properties. (Electrochemical Technology, Vol. 3, No. 11-12, pp. 335-337).
The application of metal oxide layers, and particularly aluminum oxide layers, has traditionally been performed by sputtering or electron beam techniques or by oxidation of the prior deposited metal. For example, aluminum oxide is formed by processes in which an aluminum layer is first vacuum or vapor deposited and subsequently converted to alumina (e.g., U.S. Pat. Nos. 4,190,321 and 4,158,079). Particularly when anodizing is performed to convert aluminum to alumina, high energy costs and time-consuming steps may be encountered.
The properties of the thus produced alumina layers have also been found to be less consistent than is desirable for certain applications. For example, under alkaline conditions, the alumina layer tends to separate from the substrate and may fail to hold additional polymeric layers coated thereon.
Certain metal oxides and in particular aluminum oxide have traditionally not been used in certain types of imaging processes because of difficulty encountered when etching an aluminum layer. Extreme manufacturing procedures such as the inclusion of different metals into aluminum and alumina layers in order to overcome the undesirable properties of the aluminum and alumina materials have been proposed (e.g., U.S. Pat. No. 4,008,084). These procedures have not generally provided uniform results in an economic and straightforward manner.